Carburetor



s, c. SMITH "cARBURETon Filed May 15, 1935 April 25, 1939.

. INVENTR. wYvEaAHT .5mm Y m'w/ A TTORNEY Patented pr. 25, 1939 UNITED STATES PATENT CFFICE Bendix Products Corporation, South Bend,

Ind., a corporation of Indiana Application May 13,

'l Claims.

This invention relates to carburetors and more particularly to a fuel lift carburetor.

, In one preferred embodiment of the invention,

a fuel lift venturi is employed to lift fuel from 5 a supply tankl positioned at a lower level than the carburetor. form of a rich emulsion of fuel and air, which is diluted with air supplied through another venturi, to form a suitable charge of combustible l mixture in the carburetor for the normal operation of the engine.

In carburetors of this type, it has been found difficult to control the suction exerted within the carburetor under various operating conditions lll of the engine so as to supply a combustible mixture suitable for operating the engine under varying conditions of speed and load.

It has also been found that at part throttle operation the mixture supplied to the engine by zo carburetors of this type is either too rich in fuel or too lean so that uneven operation of the engine frequently results.

An object of the present invention is therefore to provide a fuel lift carburetor, wherein a fuel lifting or booster venturi is employed to lift fuel from a supply tank positioned at a lower level than the carburetor andvmix it with a small -quantity of air, thereby producing an over-rich emulsion of fuel and air adapted to be diluted by air admitted through another venturi to produce a suitable mixture for the normal operation of the engine.

Another object of this invention is to provide a slide valve designed to control simultaneously both the venturi admitting diluting air and the venturi admitting the rich emulsion of fuel and air, so that the greatest possible flexibility in the operation of the engine may be insured.

Another object of the invention is to provide means for supplying a suitable charge of combustible mixture to the engine for normal idling operation of the engine when the throttle slide valve is moved to the fully closed position.

A still further object of the' invention is to provide means whereby a rich charge of combustible mixture may be supplied to the engine for starting the engine when it is cold.

Other objects and advantages of this invention will be apparent from the following detailed description, -together with the accompanying drawing, submitted for purposes of illustration only, and not intended to define the scope of the invention, reference being had for that purpose to the subioined claims.

In the drawing, wherein similar reference The fuel is supplied in the 1935, Serial No. 21,099

characters refer to similar parts throughout the several views:

Figure 1 is a front elevation of a carburetor embodying the present invention;

. Figure 2 is a sectional view taken on the line 5 2-2 of Figure l;

Figure 3 is a sectional view taken on the line 3 3 of Figure 2;

Figure `4 is a sectional view taken on the line 4-4 of Figure 3;

Figure 5 is an elevation on line 5-5 of Fig. l.

Referring more particularly to Figure l, there is shown a fuel lift carburetor formed in two main sections IIl and I 2. The section I8 includes an annular casing member II housing an induction passage I3. The induction passage I3 is provided with an air inlet passage I5 and a longitudinally disposed venturi I4 having a restricted section I6. The annular casing member II is designed to be engaged by a manifold or port I8, carried by an engine in any suitable manner.

Fuel is supplied to the induction passage I3 in the form of a rich emulsion of fuel and air by means of the venturis and 22, having restricted sections 24 and 26, respectively, formed in the body section I2 of the carburetor. The venturi 20 communicates with the induction passage I3 through the side walls of the venturi I4, posterior to the restricted section I6. The venturi 22 communicates with the induction passage I3 through the side walls of the venturi I4 at a. point posterior to a throttle slide valve 28, designed to obstruct the iiow of fluid through the venturis I4 and 20.

The throttle valve 28 slides in a sleeve 29, carried by the body section I0, and is provided with a manually operable member 30, whereby the valve 28 may be moved to any desired position to control the ow of air and fuel through the venturis I4 and 20. The throttle valve 28 has a rounded end section 3l designed to close both the venturis I4 and 20 as the throttle is moved to closedposition. The throttle overlaps opening I6 slightly so that. as the throttle is moved from the fully closed position to the point where diluting air begins to be admitted through the opening I6, the rate of flow through venturi 28 will be suicient to lift fuel `and cause a discharge thereof through fuel duct 36. A combustiblemixture of constant richness will therefore be supplied to the engine at all positions of the throttle valve. A stop screw 32, threaded `into the valve 28, moves in a slot 84, formed in the sleeve 28, to deilne the limits of the' move# .T55

of the throttle valve and to prevent rotation thereof. v

Fuel is supplied for normal operation of the engine through a fuel duct 36, communicating at the most restricted section 24, of the venturi 20, and provided with an adjustable needle valve 38 to control the quantity of fuel supplied to the venturi 28. An air bleed vent is provided to break up the liquid streamthrough the duct 36 to facilitate the flow of fuel to the venturi 20. As the air flows over the restricted section 24, of the venturi 20, suction is exerted on the end of the :luct 36 which will draw fuel therefrom to mix with air entering the venturi 20 to form a rich emulsion of fuel and air.

Fuel for idling operation of the engineis supplied through a fuel duct 39 which discharges at the most restricted section 26, of the venturi 22. An adjustable needle valve, similar to the valve 38, is provided to control the quantity of fuel supplied for idling operation of the engine.

The air inlet passage I5 is controlled by a choke valve 40, adapted to be manually controlled by a lever 42. It is understood, however, that, if desired, the choke valve may be controlled automatically in accordance with the temperature of the engine and/or variations of pressure existing in theinduction passage I3 posterior to the throttle valve 28. The throttle valve 28 is provided with an adjustable stop member 44, 'adapted to engage the end of the sleeve 29, to prevent the throttle valve 28 from completely closing, to provide an adjustable fast idle control mech-` anism.

The operation of this carburetor is as follows. To start the engine while it is cold, the choke valve 40 is moved to the closed position, and the throttle valve 28 is moved to the slightly open position. The engine is then cranked, Whereupon suction exerted in the induction passage I3 will draw air and fuel through the venturis 20 and 22 to provide a rich mixture for starting the engine.

As soon as the engine has started, the choke valve 40 is moved from the closed position to permit diluting air to iiow into the air inlet passage I5, to dilute the rich emulsion of fuel and air supplied through the venturis 20 and 22. The throttle valve 28 is then manipulated to supply an appropriate quantityfof combustible mixture to operate the engine at the desired.

speed. Since venturi 22 discharges at a point of less restriction in venturi I4 than does venturi 28, the amount of air` and fuel drawn through venturi 22 decreases as the throttle is opened and becomes negligible at wide open throttle.

During all normal operation of the engine a rich emulsion of fuel and air is supplied through the venturi 20.' Diluting air is admitted through the air inlet passage I5 to decrease the richness of the emulsion to provide a suitable combustible charge. V

The contour of the valve 28 is such as to subject the venturi 20 to suflicient suction to draw a. suitable charge of mixture therethrough to mix with a quantity of diluting air admitted through the alrinlet passage I5 to supply a suitable combustible charge to produce uniform operation of the engine at all speeds. A

When'it is desiredl to operate the engine at idling speed, the throttle valve 28 is moved to the fully closed position, whereupon the venturis I4 and 28 are completely closed. The suction of the engine is then exerted upon the idling venturi 22 which is so calibrated as to provide a mixture having the correct proportions of fuel and air for the successful operation of the -engine at idling speed.

While a preferred embodiment of the invention has been described in detail, it is not intended to limit the scope of the invention to the embodiment described, nor otherwise, than by the terms of the following claims.

I claim:

1. Ina carburetor for an internal combustion engine, an induction passage having an airinlet passage, a venturi in the induction passage, a primary venturi communicating with the side of the induction passage posterior 4but adjacent to the restricted section of said venturi, a fuel jet communicating with the primary venturi at the' restricted section thereof, means including a slide valve adjacent the restricted section of said venturi to simultaneously restrict the induction passage and the primary venturi, means 'including an auxiliary venturi communicating with the induction passage posterior to the primary venturi and a fuel jet communicating, with the auxiliary venturi at the restricted section thereof to supply a combustible charge to the engine when said valve is in the closed position.

2. A fuel lift carburetor having an induction passage, a secondary venturi in the induction` passage, a. primary fuel lift venturi communieating with the induction passage through the walls of the secondary venturi, a fuel nozzle communicatingwith the primary venturi, a throttle valve slidable through the walls of the secondary venturi to simultaneously eiect closing of the induction passage and the primary venturi, 'and a second primary fuel lift venturi adapted to supply a combustible mixture through the induction "passage when the throttle valve is closed. l 1

3. A carburetoihaving an induction passage, an air inlet passage, a secondary venturi in the induction passage, a'primary venturi communieating withA the induction passage through the walls of the secondary venturi immediately posterior to the restricted section thereof, a fuel jet communicating with primary venturi at the restricted section thereof, an auxiliary venturi communicating with the induction passage terior to the primary venturi, a fuel jet communi- "eating with the auxiliary venturi at the restricted section therecf, and manual means to control^ said fuel jets. e

4. A carburetor having an induction passage, an air inlet passage, a secondary venturi in the induction passage, a primary venturi communi-'- eating with the induction passage through thev walls I"of the secondary venturi immediately pos- .through the ,walls of, the secondary venturi pos terior to the restricted section thereof, a fuel l 4,iet communicating with primary venturi at the passage, an air inlet passage, a secondary ventui-i Iin the induction'passage. a primary venturi 'l5 jet communicating with the primary venturi at the restricted section thereof, manual means to control the fuel jets, a'slide valve having a rounded end section designed to progressively close the induction passage and the primary venturi as the valve is moved in the closing direction, manual means to manipulate the slide valve, and v manual means to close said air inlet passage. 6. In a carburetor for an internal combustion engine, a body section including an induction passage hav'ing' an air inlet passage and a mixture supply passage, the mixture supply passage including a primary venturi having a fuel inlet passage communicating therewith, means including va valve slidablymountedin the induction pasan idling primary venturi including a fuel inlet passage communicating with the induction passage posterior to said valve to supply a com- 5 bustible mixture to the engine when the valve is in the closed position.

'7. In a fuel lift carburetor a body section including an induction passage having an air inlet passage and a mixture supply passage, the mix- 10 ture supply passagel including a. primry venturi having a fuel inlet passage communicating therewith, means including a valveslidably mounted in the induction passage to simultaneously restrict the air and mixture supply passageways. 15 means comprising an idling'primary venturi including a fuel inlet passage communicating with the induction passage posterior to said valve to supply a combustible mixture when the valve is in the closed position, .and manually operable 20 means to vary the quantity of fuel supplied to said primaryventurl. v

, STUYV'ESANT. C; SMITH. 

